This invention relates to a wheel bearing assembly for supporting a driven wheel of an automobile.
FIG. 6 shows a conventional wheel bearing assembly of this type. It includes a homokinetic joint having an outer ring 42 formed with a plurality of ball grooves 41 in the inner surface thereof. The outer ring 42 integrally carries at its end a hub 44 having a flange 43 for supporting a vehicle wheel. The outer ring 42 and the hub cooperate to act as a wheel driving ring 40. The driving ring 40 is inserted in a cylindrical knuckle 45 fixed to the car body. A pair of counterbored outer rings 46 are disposed in the knuckle 45 with their thicker sides facing each other. Balls 47 in two rows are mounted between the respective outer rings 46 and the outer periphery of the driving ring 40 to rotatably support the driving ring 40.
The balls 47 are kept pre-loaded by means of two diametrically divided spacers 48 inserted between the opposite surfaces of the counterbored outer rings 46. The outer rings 46 and the spacers 48 are kept from coming off by a flange 49 protruding from the inner surface of the knuckle 45 at one end thereof, and a closure member 50 provided at the other end of the knuckle.
When assembling this wheel bearing assembly, the counterbored outer rings 46 are fitted onto the driving ring 40 first. Before mounting the knuckle 45 and the spacers 48, one row of balls 47 are set in position with the outer rings 46 moved axially to one side. Then, another row of balls 47 are set in position after moving the outer rings axially to the other side. In such a manner, it is possible to mount many balls. The wheel bearing assembly thus formed has a large load-bearing capacity.
As mentioned above, the counterbored outer rings 46 and the spacers 48 are kept from coming off by being sandwiched between the flange 49 formed at one end of the knuckle 45 and the closure member 50 provided at the other end of the knuckle 45. Because of this arrangement, this bearing assembly has the following problems.
Namely, the thickness of the spacers 48 disposed between the counterbored outer rings 46 varies according to the pre-load applied to the balls 47. Thus, the distance between the outer remote ends of the counterbored outer rings 46 also varies. If this distance is smaller than the distance between the inner opposite surfaces of the flange 49 of the knuckle 45 and the closure member 50, the flange 49 and the closure member 50 cannot prevent axial movement of the counterbored outer rings 46 and the spacers 48 any longer.
On the other hand, if the distance is larger than the latter distance, a gap will be formed between the knuckle 45 and the closure member 50, through which dust can easily penetrate into the bearing assembly.
An object of this invention is to provide a wheel bearing assembly which can completely prevent axial movement of the spacers for pre-loading the balls and the counterbored outer rings for guiding the balls.